Feb 12, 2024
New Arkansas blackberry performs late in season

The Arkansas Fruit Breeding Program has released a new late-season blackberry to give growers a premium product after other varieties are done yielding.

Commercial scale propagators have licenses and material for sale for the 2024 planting season.

Sweet-Ark Immaculate blackberry
The Arkansas Fruit Breeding Program has released a new thornless blackberry, Sweet-Ark Immaculate. Photo by Paden Johnson.

Sweet-Ark Immaculate is a trademarked thornless, floricane-fruiting blackberry that offers medium to large berries that have been shown to hold up well after harvest. Floricane varieties produce flowers and fruit on second-year canes.

“It is named to highlight its berry quality, which is beyond reproach, and its late-ripening season,” said Margaret Worthington, director of the Fruit Breeding Program for the Arkansas Agricultural Experiment Station. “People have been asking about a new late-season variety from the Arkansas program for a long time now. The main advantages Sweet-Ark Immaculate has over other late-season blackberry varieties are its outstanding postharvest performance and its great yield potential.”

The experiment station is the research arm of the University of Arkansas System Division of Agriculture.

Worthington said Sweet-Ark Immaculate demonstrates a step forward for blackberry firmness, which aids in holding up well during storage and shipping. Postharvest trials at the Fruit Research Station near Clarksville, Arkansas, show that Sweet-Ark Immaculate had better fruit firmness than all comparison cultivars after two weeks of refrigerated storage.

Maintaining quality in postharvest storage is especially challenging late in the season, Worthington added, because it is when temperatures are high and spotted wing drosophila pest pressure increases.

Despite its late-ripening window, red drupelet reversion and leak ratings for Sweet-Ark Immaculate were similar to earlier season varieties like Sweet-Ark Caddo and Sweet-Ark Ponca, she noted. Red drupelet reversion occurs when the individual round segments on the blackberry turn from black back to red during or after postharvest storage.

Late-season love

Late-season varieties are treasured for growers in the shipping industry to command a higher premium because less fruit is available during that period. Worthington said it is also nice for local growers who can have fruit available at farmers markets, fruit stands or pick-your-own operations later in the season.

At the Fruit Research Station, Sweet-Ark Immaculate is typically ready to pick the last week of June through mid-to-late July. Worthington noted that this period is 10 to 14 days after the harvest of Ouachita but in season with Navaho and Von.

Like Sweet-Ark Ponca, Sweet-Ark Immaculate has shorter-than-standard canes and a reduced space between leaves, also known as the internode length.

“It fills the trellis, but the first-year canes are a little bit shorter than standard,” Worthington said. “This has an advantage for growers because you don’t have to tip during the busy season when harvesting fruit. So, it can spread out the workload a little bit.”

The term “tipping” refers to summer pruning on new blackberry canes performed during the growing season to manage plant height and increase yields by promoting lateral branching.

Including Sweet-Ark Immaculate, the Arkansas Fruit Breeding Program has publicly released 22 blackberry varieties, with 16 of those being floricane fruiting.

Sweet-Ark Immaculate is available for licensing to propagators. Contact the Technology Commercialization Office for licensing information at 479-575-3953 or at [email protected].

— University of Arkansas Department of Agriculture




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